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Hayabusa - The Return To Earth, The voyage home
RNeuhaus
post Nov 30 2005, 04:00 AM
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QUOTE (nop @ Nov 29 2005, 10:16 PM)
Dear 5thstar (if you read this forum), ljk4-1, odave and other guys,

Very sorry for my misleading post.  I posted it just as a fan feeling a sympathy for 5thstar's message and I also believe that Prof. Kawaguchi is already doing what to do.

Anyway, sorry if you felt unpleasant, and thank you for your kind replies.
*

Hello Nop,

Don't worry of your post. This forum is open. Everybody shares the information and we respect the opinion and feeling from others. We are tolerant and educated people as you! biggrin.gif

Rodolfo
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hugh
post Nov 30 2005, 12:40 PM
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QUOTE (odave @ Nov 29 2005, 03:40 PM)
Kawaguchi: We can extend it to the mid of December, if it has only to return.


But after that, Kawaguchi said that a later return (after early December) means a different (sharper?)re-entry angle, and that the re-entry capsule has little margin to withstand the extra heat.
It doesn’t sound too good. One Hayabusa project manager was quoted weeks ago as being “not optimistic” about there being enough propellant for an earth return at the present rate of usage. That was before the 30-minute “stay” on Itokawa and the leaky thruster, and all the other systems problems. It’s far from over yet, but it might be too high a hill for them to climb….
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deglr6328
post Dec 1 2005, 12:04 AM
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Grist for the Moomaw mill biggrin.gif ...

This from the Nature online news article...

"The mission is renewing Japan's confidence in space activities. JAXA has recently tried a string of high-risk missions, but has seen many failures over the past few years. "Hayabusa's success has become a tailwind for Japan's space development," Hajime Inoue, JAXA's executive director, said at a press conference. "It proves that the way we have been doing things wasn't wrong."

blink.gif blink.gif I hope that is a translation gaffe and they really don't think that everything is a-ok with thier whole program because of a recent streak of (much needed) luck!
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Guest_BruceMoomaw_*
post Dec 1 2005, 12:35 AM
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Oh dear, oh dear, oh dear. Pride goeth before a leak.
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helvick
post Dec 1 2005, 12:48 AM
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Nice detailed update from Emily over at The Planetary Society
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RNeuhaus
post Dec 1 2005, 02:24 AM
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Dramatic news extracted from Planetary.org:

At this point, Hayabusa's exact location is unknown, although Kawaguchi said that it is "still within several kilometers from Itokawa." Moreover, he added, "there is little chance" they will lose touch with Hayabusa again, at least in terms of where it is now.

Not yet know where Hayabusa is located, perhaps it might fall on Itokawa due to the gravity tug and/or by the Sun wind pressure which is pushing it toward to Itokawa if it is located on the south of Itokawa (the South Polar of Itokawa faces to Sun and Earth).

Rodolfo
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mike
post Dec 1 2005, 04:18 AM
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If Hayabusa's thrusters persist in being only half-useful, traveling with the asteroid until it gets closer to Earth may be the only choice - unless of course they won't be able to generate enough thrust before Earth flies away regardless.. Yet another cliffhanger.
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ElkGroveDan
post Dec 1 2005, 05:40 AM
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QUOTE (mike @ Dec 1 2005, 04:18 AM)
If Hayabusa's thrusters persist in being only half-useful, traveling with the asteroid until it gets closer to Earth may be the only choice - unless of course they won't be able to generate enough thrust before Earth flies away regardless..  Yet another cliffhanger.
*

My understanding is that they have a heating system of some kind but are cautious about collateral effects from too much heat. I would guess that if it came to an all-or-nothing point they could decide to take their chance and try to heat up the frozen thrusters.


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ljk4-1
post Dec 2 2005, 07:53 PM
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Would it be possible to send out a probe to snag Hayabusa and bring it back to Earth with its surface samples? Or maybe remove just the samples and bring them back?

I think either scenario would be easier than trying a landing again on the planetoid at this point.


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"After having some business dealings with men, I am occasionally chagrined,
and feel as if I had done some wrong, and it is hard to forget the ugly circumstance.
I see that such intercourse long continued would make one thoroughly prosaic, hard,
and coarse. But the longest intercourse with Nature, though in her rudest moods, does
not thus harden and make coarse. A hard, sensible man whom we liken to a rock is
indeed much harder than a rock. From hard, coarse, insensible men with whom I have
no sympathy, I go to commune with the rocks, whose hearts are comparatively soft."

- Henry David Thoreau, November 15, 1853

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RNeuhaus
post Dec 2 2005, 08:31 PM
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There many options. Wait for a while until before than December 10, next saturday to know what will be the final decision for the home return.

1) Travel along with Itokawa and then direct toward to Earth alone (more than 3 years). Their risks are on the power supply or batteries when it approaches to Mars' orbit where there are less sun radiation.
2) Travel alone back home (1 1/2 year). It depends upon to the health of thrusters.
3) Travel along with Itokawa and then wait for a rendezvous probe which will tug it until dropping to Earth.
4) Land on Itokawa and stay dormant upon the future visit.
5) Abandon it to his fate by wandering on the space.

Rodolfo
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Bob Shaw
post Dec 2 2005, 08:34 PM
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QUOTE (mike @ Dec 1 2005, 05:18 AM)
If Hayabusa's thrusters persist in being only half-useful, traveling with the asteroid until it gets closer to Earth may be the only choice - unless of course they won't be able to generate enough thrust before Earth flies away regardless..  Yet another cliffhanger.
*


Mike:

Er, probably not a good idea.

Hayabusa will be expected to travel on some strange variant of a Hohmann minimum-energy orbit (with both Earth's orbit and that of the asteroid being gently touched at start and end of the mission). A 'strange variant' because it's flightpath is constantly altering under the influence of it's ion engines, and active control of the spacecraft (a la SMART-1) will be crucial during the return. So, unlike a traditional 'single impulse' trajectory (with perhaps a couple of tweaking burns halfway or so) Hayabusa can't be left dormant during cruise but will require good communications and good attitude control throughout.

You can't get round this by 'hitching a ride' on a nearby asteroid!

Bob Shaw


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Bob Shaw
post Dec 2 2005, 08:45 PM
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QUOTE (RNeuhaus @ Dec 2 2005, 09:31 PM)
There many options. Wait for a while until before than December 10, next saturday to know what will the final decision for the home return.

1) Travel along with Itokawa and then direct toward to Earth alone (more than 3 years) Their risks are on the power supply or batteries when it approaches to Mars' orbit.
2) Travel alone back home (1 1/2 year). Depends upon to the health of thrusters
3) Travel along with Itokawa and then wait for an rendezvous probe which will hawl it until dropping to Earth.
4) Land on Itokawa and stay dormant upon the future visit.
5) Abandon it to his fate by wandering on the space.
*


I really think there are very few options!

Option 1) - waiting on-station until the next interplanetary line-up (which might well be many years in the future) *might* work with a probe designed for longevity. Not with Hayabusa, though!

2) - Correct, and the only way to get back home at all.

3) - No, for all sorts of reasons, not least being the fact that we can't even reliably perform such missions in Earth orbit, never mind the depths of space. Anyway, who's paying for a rescue flight - nobody!

4) - 'Dormant' as in, er, deceased. An ex-spacecraft, pining for the Norwegian fjords. I suppose it'd keep the Solar system that bit tidier, and we might see some more closeups on the way down.

5) - Sadly, the most likely outcome. An ion-drive probe has to be *much* smarter and controlled than traditional single-impulse 'artillery' probes, and if the RCS system is almost broken then it's highly unlikely that it'll do more than limp in the general direction of Earth before settling into Solar orbit when the ion drive stops working (at which time we're back in the realms of 'artillery').

Hayabusa is, make no mistake about it, a success - even if no return to Earth is feasible, then it will have carried out an outstanding mission of which JAXA should be very proud.

Bob Shaw


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odave
post Dec 3 2005, 02:06 PM
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5thstar's blog has a few new Hayabusa updates.

QUOTE
No official information from JAXA yet.

JIJI press issued an article. Prof. Matogawa replied to a query from media saying JAXA will complete taking necessary data by December 5, and will try to analyze the cause of the malfunction and resume the recovery operation.

[...]

Next press briefing by JAXA/ISAS is not likely on or before December 5.


They're still not saying anything about the thrusters. Hopefully no news = no news at this time unsure.gif


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RogueEngineer
post Dec 7 2005, 12:58 PM
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QUOTE (odave @ Dec 3 2005, 11:06 PM)
Hopefully no news = no news at this time  unsure.gif
*

Another bad news... They are still struggling in the recovery operation, and the bullet may not be fired during the second touchdown attempt on Nov. 26th. See English translation in the comment area of
Matuura's blog 2005.12.07 #1
Matuura's Blog 2005.12.07 #2
for details.
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Guest_BruceMoomaw_*
post Dec 7 2005, 02:07 PM
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Are they actually saying that they themselves accidentally programmed the craft with a command NOT to fire the bullet, or just that the spacecraft set itself back to a safe mode that kept it from doing so?

At any rate, it looks more and more as though Hayabusa is going to confirm all my dark warnings about the unwisdom of trying to do too complex a space mission with much too little money. (There is, by the way, a lengthy article in this week's Aviation Week suggesting that JAXA has very belatedly caught onto this fact.)
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